1. Field of the Invention
The present invention relates to disk drive devices and, more particularly, to improvement in the airtight structure of disk drive devices.
2. Description of Related Art
Recently, there has been a rapid development in the technology for improving the recording density of a fixed disk drive device (hereinafter, simply referred to as a disk drive device). In association with this, the recording capacity has been increased dramatically. In association with the improvement in the recording density, measures against the invasion of foreign materials into a disk drive device have become a concern. For example, the distance between the surface of a recording disk accommodated inside a disk drive device and the magnetic head is on the order of several nanometers. In contrast, the size of dust etc. in the air is far larger so that the dust invading the disk drive device may cause failure of the magnetic head to access the recording disk or cause a physical damage to the recording disk or the magnetic head. For this reason, the housing of the disk drive device needs to have a sealed structure. Meanwhile, the disk drive device accommodates a motor for driving the recording disk into rotation, and a magnetic head. Thus, there is a need to guide leads for feeding power to a magnetic coil of the motor or signal leads of the magnetic head outside the disk drive device. The leads are guided outside via a through hole formed in a part of the housing of the disk drive device. As mentioned above, the housing needs to have a sealed structure. Therefore, the portion of the device where the lead is guided through needs to be highly airtight in order to prevent air leak.
Various structures for ensuring the airtightness of the housing are proposed. Known such structures include a structure wherein a seal is placed in the through hole portion and a sealant is applied on the portion, a structure where a plug hole is sealed by solder, a structure where a bush is placed in the through hole and the hole is sealed by applying a plurality of types of adhesives.
However, the sealant, solder, and adhesive all have fluidity and can easily run in the process of coating and curing. Disadvantageously, this is likely to cause variation in the condition of sealing, causing product to product variation, and resulting in the unstable airtight performance in the through hole portion. The related-art approach is also disadvantageous in that it requires the addition of a structure for minimizing the flow of whatever is applied or the addition of a step that allows for flowability, resulting in an increase in the manufacturing cost.